The present invention relates to a folding structure for a treadmill and which includes two sub-wheels movably received in the side rails of the base of the treadmill and the sub-wheels come out from two openings of the side rails to contact the floor when the treadmill is folded.
A conventional treadmill is shown in FIGS. 8A and 8B and generally includes a base 72 which is pivotably connected to the frame 70 on which the belt of the treadmill is installed. A lifting mechanism 73 is connected to the base 72 and includes links 731 which has one end connected to a motor and worm system and the other end of the links 731 has a wheel 732 connected thereto which contacts the floor. Two sub-wheels 721 are located at an end of the base 72 so that when the frame 70 is located at a horizontal position as shown in FIG. 8A, the wheels 732, the sub-wheels 721 and the two legs 711 on the frame 70 contact the floor to support the frame 70. When the frame 70 is lifted at an angle relative to the floor frame 70, the sub-wheels 721 are lifted as shown in FIG. 8B. As shown in FIG. 7, when the frame 70 is folded to an upright position, only the wheels 732 contact the floor so that the whole treadmill moves on the floor and it is inconvenient to fold in up.
The present invention intends to provide a folding structure that includes two sub-wheels movably received in the side rails of the base and the two sub-wheels come out from two openings in the side rails so as to contact the floor to support the balance of the folded treadmill.
In accordance with one aspect of the present invention, there is provided a foldable treadmill which comprises a base having two hollow side rails and two openings are defined through an underside of the two side rails respectively. A slot is defined in an inner side of each of the two side rails and communicates with an interior of each side rail. Two arms of a handle are connected to the two side rails. A frame has two sides and two links are pivotably connected between the two arms of the handle and the two sides of the frame. An assistant frame is located between the two side rails of the base and has a first transverse bar. Two support links are connected to the first transverse bar and the underside of the frame. Two sub-wheels are connected to the two ends of the first transverse bar and movably received in the interior of the two side rails via the slots. The sub-wheels come out from the two openings when the frame is upright folded.